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Organic disulfanes (also named disulfides) play a vital role in chemistry and biology.1–4 In particular, unsymmetrical disulfanes are a class of important molecules with bioactivities,1–4 such as a...

A series of novel 1,4-naphthoquinones possessing pyrido[2,3-d]pyrimidine scaffolds were synthesized in very good yields using one-pot condensation of 2-hydroxy-1,4-naphthoquinone, aldehydes, and 2-substituted 4,6-diaminopyrimidine. The in vitro anti-proliferative activity of these novel compounds was evaluated in SGC7901 and HepG2 cell lines. Almost all the tested compounds showed manifested potent inhibitory activity against the two tested cancer cell lines.

This chapter is devoted to unravel the relaxation processes taking place after photoexcitation of isolated DNA/RNA nucleobases in gas phase from a time-dependent perspective. To this aim, several methods are at hand, ranging from full quantum dynamics to various flavours of semiclassical or ab initio molecular dynamics, each with its advantages and its limitations. As this contribution shows, the most common approach employed up to date to learn about the deactivation of nucleobases in gas phase is a combination of the Tully surface hopping algorithm with on-the-fly CASSCF calculations. Different dynamics methods or, even more dramatically, different electronic structure methods can provide different dynamics. A comprehensive review of the different mechanisms suggested for each nucleobase is provided and compared to available experimental time scales. The results are discussed in a general context involving the effects of the different applied electronic structure and dynamics methods. Mechanistic similarities and differences between the two groups of nucleobases - the purine derivatives (adenine and guanine) and the pyrimidine derivatives (thymine, uracil, and cytosine) - are elucidated. Finally, a perspective on the future of dynamics simulations in the context of nucleobase relaxation is given.

A ceria nano catalyst was used for the one-pot, multi-component condensation reaction of benzoylacetonitrile, aromatic aldehydes and 5-aminotriazole/5-aminotetrazole, and proceeds via C–C and C–N bond formation to deliver the desired triazolo/tetrazolo[1,5-a]pyrimidine derivatives. This protocol provides cleaner conversion with high selectivity and shorter reaction times. The CeO2 nanoparticles were prepared by a simple coprecipitation method and characterized using XRD, TEM, and XPS techniques.

2-Thiazolylhydrazonomalononitrile (1) was used as key intermediate for the synthesis of polyfunctionally substituted heterocycles (e.g. pyridazine, tetrazole, pyrimidines, 1,5-benzo diazepine, benzoimidazo[1,2-a]pyrimidine, triazolo[4,3-a]pyrimidine, pyrazole, pyrazolo[1,5-a]triazines, pyrazolo[1,5-a]pyrimidine and 1,5-benzoxazocine) incorporating thiazole moiety via its reactions with some carbon and nitrogen nucleophiles. Structures of the newly synthesized compounds were established by elemental analysis and spectral data. The mechanistic aspects for the formation of the new compounds were also discussed.

The introduced protocol has the advantages of readily available starting materials, short reaction times, and good regioselectivity.

A simple and facile synthesis of fused tetrazolo[1,5-a]pyrimidine derivatives based on the multicomponent reaction of acetophenone, dimethylformamidedimethylacetal and 5-aminotetrazole is described. A green chemical synthesis has been achieved by using1-butyl-3-methylimidazolium hydrogen sulfate [Bmim]HSO4 ionic liquid as a reusable medium. Short synthetic route, operational simplicity, good yields, eco-friendliness and recyclability of the ionic liquid are the advantages of this method. The synthesized compounds were screened for α-glucosidase inhibitory activity using yeast maltase (MAL12) as a model enzyme. Inhibition and kinetic studies have shown that compounds 4d and 4g are found to be active showing comparable inhibitory potency with acarbose. Further docking studies of the derivatives with MAL12 homology model identified a similar binding mode consistent with the binding of acarbose. These studies along with in silico predicted ADMET properties suggest that these molecules could represent a new scaffold that may be useful for the development of new anti-diabetic drugs.

New pyrido[2,3-d]pyrimidines , , , and have been synthesized. The vasorelaxant effect on smooth muscle isolated from rat aorta, via PDEs inhibition, of these compounds along with other pyrido[2,3-d]pyrimidines reported earlier by our group, has also been determined. These pyrido[2,3-d]pyrimidines were synthesized by the reaction of ferrocenyl-ethynyl ketones () or α-alkynyl ketones () with 6-amino-1,3-dimethyluracil using [Ni(CN)4]−4 as an active catalytic species, formed in situ in a Ni(CN)2/NaOH/H2O/CO/KCN aqueous system. Evaluation of the vasorelaxant effect of compounds demonstrated that all compounds relax the tissue in a concentration-dependent manner. The structural changes do not alter the effectiveness; however, there are differences related to potency expressed as EC50. Compounds (7-ferrocenyl-1,3-dimethyl-5-(m-tolyl)-pyrido[2,3-d]pyrimidine) and (7-ferrocenyl-1,3-dipropyl-5-(4-metoxyphenyl)-pyrido[2,3-d]pyrimidine) were the most potent compounds, even more than rolipram, reference drug; the EC50 was 0.41 ± 0.02 μM and 0.81 ± 0.11 μM for and , correspondingly. The EC50 of compounds (7-ferrocenyl-1,3-dimethyl-5-phenyl-pyrido[2,3-d]pyrimidine), (7-ferrocenyl-5-(3,5-dimethoxyphenyl)-1,3-dimethylpyrido[2,3-d]pyrimidine), and (5-n-butyl-7-ethyl-1,3-dimethylpyrido[2,3-d]pyrimidine) was similar to EC50 of rolipram. Compounds significantly induce concentration-dependent vasorelaxation in endothelium-intact aortic rings. In addition, the relaxation responses to each compound in either endothelium-intact or endothelium denuded aortic rings were comparable, suggesting that removal of the functional endothelium has no significant influence on its intrinsic vasorelaxant activity. In vitro capability of conserving cyclic-AMP or cyclic-GMP (adenosine and guanosine 3′, 5′-cyclic monophosphate) via PDE inhibition for compounds and was evaluated. Compounds and show the highest percent inhibition effect (94.83% and 83.98%, respectively) for the decomposition of c-AMP. Docking studies showed that the compound was selective for the inhibition of PDE-4.

The synthesis and regioselective functionalization of rare 2,4-disubstituted-pyrido[1′,2′:1,5]pyrazolo[3,4-d]pyrimidine derivatives is reported. C-4 aminations were performed by chlorine nucleophilic substitution SNAr reactions, and their efficiencies were compared with those for direct one-pot amide C–O activation with bromotripyrrolidinophosphonium hexafluorophosphate (PyBroP) as a reagent. The latter method was used to perform palladium-catalyzed C-4 (het)arylation. Finally, two C-4 amino and aryl derivatives were prepared on a large scale and engaged in desulfurative Liebeskind–Srogl-type reactions under microwave irradiation to afford the envisioned compound library. Each step was optimized, and the results are discussed.

Multicomponent reactions make up an important subclass of azaheterocycle syntheses. In this report, a mild and catalyst-free multicomponent preparation of 1 H -pyrazolo[3,4- b ]pyridines is described. This one-pot synthesis uses simple aldehyde, 3-oxopropanenitrile, and 1 H -pyrazol-5-amine starting materials to rapidly access structurally diverse products. Additionally, the impact of 1 H -pyrazol-5-amine C3 substituents on the formation of 1 H -pyrazolo[3,4- b ]pyridines vs pyrazolo[1,5- a ]pyrimidine structural isomers is discussed.

A simple and direct procedure was developed for the synthesis of a novel series of polyfunctionalized pyrimidines. They were prepared via reaction of N-(substituted carbamothioyl)benzimidamides (prepared from the reaction of benzimidamide hydrochloride and isothiocyanates) and malononitrile in the presence of CuBr/Et3N in DMF at 80 °C.

Novel tricyclic pyrimido[1,2-b]indazole-3-carbonitrile derivatives containing both biologically active pyrimidine and indazole templates are synthesized by three-component reaction of 1 H -indazol-3-amine, aldehydes, and malononitrile catalyzed by base di- n -butylamine (DBA) in ethanol. This synthesis was confirmed to follow the group-assisted-purification (GAP) chemistry process, which can avoid traditional chromatography and recrystallization purifications.

A new synthetic method in pyrimidine chemistry has been developed. 2,2,2-Trichloroethylideneacetophenones, easily available from chloral and acetophenones, reacted with benzamidines to provide novel 2,6-diaryl-6-hydroxy-4-trichloromethyl-1,4,5,6-tetrahydropyrimidines in near quantitative yields. Efficient dehydration of these compounds gave previously unknown 2,4-diaryl-6-trichloromethyl-1,6-dihydropyrimidines, which were found able to undergo base-induced chloroform elimination to give 2,4-diarylpyrimidines in high yields. Molecular structures for final and intermediate compounds were determined by single crystal X-ray diffraction. A main improvement of this procedure lies in circumventing the oxidative aromatization of dihydropyrimidine intermediates through a chloroform elimination process. The diarylpyrimidines were also found directly accessible by a fair yield one-pot procedure.

We have developed an efficient one-pot reaction for the synthesis of 2,4-dihydroxy-6-phenylethylenyl-8-deazapteridine derivatives using 2,4-dihydroxy-6-methylpyrido[3,2-d]pyrimidine, aromatic aldehydes and p-toluenesulfonamide through C(sp3)–H bond functionalization. This method is easy to operate and high-yielding, which is potentially useful for diversity-oriented synthesis.

An efficient synthesis of pyrido[2,3-d]pyrimidine derivatives via one-pot multicomponent reactions of 6-amino-2-(alkylthio)pyrimidin-4(3H)-one, 3-cyanoacetylindole and arylaldehydes using [Fe3O4@ZrO2] as magnetically recyclable nanocatalyst is reported. This protocol furnished the desired products in good to excellent yields (70–93 %) and lower reaction times. The catalyst could be easily and efficiently separated from the final product solution by an external magnet and be reused in 5 consecutive runs without any significant activity decrease.

starting from aminopropynylpyridinium bromide derivatives and aromatic sulfonyl azides involving a novel application of ketenimines

A silver catalyzed cyclization of acetylene amine was developed to synthesize 4,6-substituted pyrrolo[3,2- d ]pyrimidine, a bioactive isosteric scaffold of purine. Starting from simple commercially available acetylenes and pyrimidines, the method was found to be compatible with wide chemical functionalities, leading to a series of pyrrolo[3,2- d ]pyrimidines in 84–91% yields.

The design, development and application of an efficient procedure for the concise synthesis of the 1,3-syn- and anti-tetrahydropyrimidine cores of manzacidins are reported. The intramolecular allylic substitution reaction of a readily available joint urea-type substrate enables the facile preparation of both diastereomers in high yields. The practical application of this approach is demonstrated in the efficient and modular preparation of the authentic heterocyclic cores of manzacidins, structurally unique bromopyrrole alkaloids of marine origin. Additional features of this route include the stereoselective generation of the central amine core with an appending quaternary center by an asymmetric addition of a Grignard reagent to a chiral tert-butanesulfinyl ketimine following an optimized Ellman protocol and a cross-metathesis of a challenging homoallylic urea substrate, which proceeds in good yields in the presence of an organic phosphoric acid.

The present review provides a study on the structural features, reactions, and synthetic methodologies of pyrido[1,2-c]pyrimidines. The maximum deviation from the mean plane of the pyridopyrimidine skeleton of 4-(pyridin-2-yl)-1H-pyrido[1,2-c]pyrimidine-1,3(2H)-dione indicated a reasonably planar system. The aim of this review is to give an overview of the diverse methodologies that have been reported on the chemistry of pyrido[1,2-c]pyrimidines. The different synthetic routes have been grouped according to the way the pyrido[1,2-c]pyrimidine moiety has been created. Thus, pyrido[1,2-c]pyrimidine compounds were obtained by the formation of one bond α to the bridgehead nitrogen atom [6+0(β)] and formation of two bonds from ([3+3], [4+2], and [5+1]) atom fragments. The mechanistic pathways of the reactions are discussed.

Direct C–H functionalization of triazolo[a]-annulated 8-azapurines with phenol ethers or thiophene has been performed using the oxidative nucleophilic displacement of a hydrogen on the pyrimidine ring, proceeding through the intermediacy of the corresponding σH-adducts.

Here, we report a metal-free cross-coupling reaction of diazines and related heteroarenes with organoboron species via C–H functionalization. The optimized conditions represent a metal-free method for the activation of aryl/heteroarylboronic acids, which undergo coupling with diazines and related heteroarenes. Optimized conditions also find application in the synthesis of a pyrimidine-based potent CDK inhibitor, meriolin1.

The title pyrimidine derivatives are prepared by reaction of aminopyridines and aconic acid.

Synthesis of pyrazolo[1,5-a]pyrimidines, [1,2,4]triazolo[1,5-a]pyrimidine, 8,10-dimethyl-2-(5-methyl-1-phenyl-4,5-dihydro-1H-1,2,3-triazol-4-yl)pyrido[2′,3′:3,4]-pyrazolo[1,5-a]pyrimidine, benzo[4,5]imidazo[1,2-a]pyrimidine via heterocyclic amines, and sodium 3-hydroxy-1-(5-methyl-1-phenyl-1H-1,2,3-triazole-4-yl)prop-2-en-1-one were carried out. Also, synthesis of isoxazoles, and pyrazoles from sodium 3-hydroxy-1-(5-methyl-1-phenyl-1H-1,2,3-triazole-4-yl)prop-2-en-1-one and hydroxymoyl chlorides and hydrazonoyl halides, respectively, were made. Analogously, (1,2,3-triazol-4-yl)thieno[2,3-b]pyridine derivatives were obtained from sodium 3-hydroxy-1-(5-methyl-1-phenyl-1H-1,2,3- triazole-4-yl)prop-2-en-1-one and cyanothioacetamide followed by its reacting with active methylene compounds. In addition to full characterization of all synthesized compounds, they were tested to evaluate their antimicrobial activities, and some compounds showed competitive activities to those of tetracycline, the typical antibacterial drug, and clotrimazole, the typical antifungal drug.

This review presents a systematic and comprehensive survey of the method of preparation and the chemical reactivity of 2-acetylphenothiazines. The target compounds are important intermediates for the synthesis of a variety of synthetically useful and novel heterocyclic systems with different ring sizes such as isoxazole, pyrazole, pyrimidine, pyridine, quinolone, pyrazolo[3,4-d] pyridazine, 1,5-benzothiazepine, and triazolo[1,5-a] pyridine.

This account aims to describe our recent efforts on the synthesis and utilization of N-containing heterocycles, where transition metals participate in the synthesis. A variety of nitrogen sources, including amines, amides, hydrazones, pyrimidines, isocyanides, and copper nitrate, have been disclosed for the synthesis of diverse bioactive and pharmacologically interesting N-containing heterocycles under the participation of transition metals. The well-known nitrogen sources, such as amines and amides, were used for the construction of indoles, isatins, and quinolones. Dihydrophthalazines, isoquinolines, indazoles, and pyrazoles were obtained from hydrazones, while various pyrimidine-containing heterocycles were afforded through regioselective C-H functionalizations using pyrimidine as the directing group. Recent research has focused on the chemistry of isocyanides to achieve several kinds of heterocyclic compounds with high efficiency under the catalysis of transition metals (Pd, Rh, Mn, Cu), through oxidative cyanation reactions, sequential isocyanide insertions into C-H, N-H, or O-H bonds, and tandem radical annulation. More recently, an efficient route to isoxazolines has been reported using copper nitrate as a novel nitrogen source.

The reaction of 4-aryl-6-bromomethyl-5-nitro-3,4-dihydropyrimidin-2(1H)-ones, containing three possible combinations of substituted and unsubstituted nitrogen atoms with anilines depending on the conditions leads to the products of ring contraction of the pyrimidinone ring into an imidazolone, as well as to the formation of 7-aryl-6,7-dihydroisoxazolo[4,3-d]pyrimidin-5(4H)-one derivatives, and in some cases to the 5-aminopyrimidinones. The mechanisms of these unusual ring transformations are discussed.

Using β-cyclodextrin (β-CD) as a catalyst pyrimidine derivatives were synthesized for the first time in aqueous medium. β-CD is a recyclable, inexpensive, economically viable, non-toxic, and readily available material. Various aldehydes were used with ammonium acetate, and 1,3-diketones to generate a series of pyrimidine derivatives in good to excellent yields.

New fluorescent compounds, 2-substituted indeno[1,2-d]pyrimidin-5-ones (3a, 3b, 3c, 3d) were synthesized in good yield by the reaction of 2-[bis(methylsulfanyl)methylene]indan-1,3-dione (1) with the respective amidine derivatives [guanidine carbonate (2a), acetamidine hydrochloride (2b), S-methylisothiourea sulfate (2c), and S-benzylisothiourea sulfate (2d)]. 4-Substituted amino-2-aminoindeno[1,2-d]pyrimidin-5-ones (7b, 7c, 7d) were synthesized by a one-pot reaction of 1, 2a and the respective amine compounds (4b, 4c, 4d) in pyridine. These fused pyrimidine derivatives showed fluorescence in the solid state.

Nucleoside analogues belong to an important class of antiviral and anticancer drugs. Insertion of a methylene fragment between the anomeric carbon and pyrimidine or purine bases transforms nucleosides into 1'-homonucleosides. When compared with nucleosides this modification lengthens the separation between HO-C5' of pentofuranoside fragments and nitrogen (N1 or N9) atoms of nucleobases, lowers the steric and electronic interactions between nucleobases and sugar rings, introduces greater flexibility around a CH2-Base bond and thus allows for more rotational freedom, and since the anomeric effect no longer operates any sugar or pseudosugar moiety exists in its unique conformation and experiences specific conformational mobility and hydrolysis of the C1'-CH2Base bond by cellular enzymes is no longer feasible. This review covers 1'-homonucleosides with a tetrahydrofuran ring and its nitrogen and sulfur analogues as well as those containing a cyclopentane moiety as a sugar replacer. Achievements in syntheses of sugar or pseudosugar scaffolds are of primary interest since pathways to install nucleobases are well recognized. Whenever possible, the biological activity, mostly antiviral and antitumor but sometimes as inhibitors of specific enzymes, will be presented and discussed to help identify structural features responsible for the particular mode of action and thus possible therapeutic significance.

The Cu-catalyzed oxidation of ketones with O2 has recently been extensively utilized to cleave the α-C–C bond. This report examines the selective aerobic hydroxylation of tertiary α-C–H bonds in ketones without C–C cleavage. We set out to understand the underlying mechanisms of these two possible reactivity modes. Using experimental, in situ IR spectroscopic, and computational studies, we investigated several mechanisms. Our data suggest that both C–C cleavage and C–H hydroxylation pathways proceed via a common key intermediate, i.e., an α-peroxo ketone. The fate of this peroxide dictates the ultimate product selectivity. Specifically, we uncovered the role of hppH [= 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine] to act not only as a base in the transformation but also as a reductant of the peroxide to the corresponding α-hydroxy ketone. This reduction may also be accomplished through exogenous phosphine additives, therefore allowing the tuning of reduction efficiency toward higher driving forces, i...

A new palladium-catalyzed, heteroatom-directed strategy for C–H nitration of anilines is described. This C–H functionalization reaction is highly ortho-selective and results in very good yields. The highlight of the work is the use of pyrimidine as the removable directing group. This approach constitutes one of the rare methods of ortho-nitration of anilines, a reaction that is normally very difficult to achieve via traditional approaches.

An endeavour has been made towards the synthesis of uracil based compounds in good to high yield catalyzed by nano-Ag at 70 °C upon reacting 6-amino-1,3-dimethyluracil and indole derivatives. The catalyst was potentially recyclable from fresh up to the third run.

Racemic 4-oxocyclopent-2-en-1-yl acetate was used in a short synthesis of nucleoside analogues with pyrimidine and purine heterobases. The protocol is based on a typical nucleophilic substitution process. Uracil, thymine, 6-chloropurine, and some adenines gave the expected 4-heterosubstituted products along with the isomeric 2-heterosubstituted compounds as minor components. Samples of selected products were evaluated for their antiviral activity in a primary screening against a variety of viruses belonging to different classes. One of the compounds was found to be highly active against human papilloma virus (HPV).

A convenient method for the regioselective synthesis of unsaturated nucleoside analogs in water under microwave irradiation was developed. All pyrimidine and purine nucleoside derivatives were exclusively alkylated at N1 and N9 respectively in good to excellent yields. In addition, this system could tolerate a broad range of functional groups, such as chloro, bromo, iodo, alkyl, amino, and hydroxyl groups. More importantly, the reaction scale could be enlarged to 50 mmol which made this route attractive for industrial application.

[1,2,4]Triazolo[1,5-a]pyrimidines are very interesting and trend class of fused heterocycles due to their valuable biological properties. Some [1,2,4]-triazolo[1,5-a]pyrimidines possess herbicidal activity,1 also they can act as antifungal,2 antitubercular,3 and antibacterial4 agents. Polycyclic systems containing [1,2,4]triazolo[1,5-a]-pyrimidine moiety are reported as antitumor,5 as corticotropin-releasing factor 1 receptor antagonists6 or calcium channel modulators;7 they can be used for treatment of Alzheimer's disease8 and insomnia.9 Complexes of triazolo-pyrimidines with Pt and Ru are highly active against parasites10 and can also be used in treating cancer.11 The synthetic ways for the preparation of [1,2,4]triazolo[1,5-a]-pyrimidines can be divided into two main groups: annulation of pyrimidine moiety to triazole ring and annulation of triazole fragment to pyrimidine ring. The Dimroth rearrangement of [1,2,4]triazolo[4,3-a]pyrimidines can also be used for the synthesis of [1,2,4]triazolo[1,5-a]pyrimidines. In this review article we have focused on synthetic approaches for the creation of [1,2,4]triazolo[1,5-a]pyrimidine system.

The title compounds are prepared by a facile domino one-pot protocol involving pseudo three-component, three-component or four-component reactions.

Carbocyclic nucleosides are considered as nucleoside mimetic having high therapeutic potentials, however diverse exploration is still limited due to their synthetic difficulties. The major challenges are associated with the preparation of new base and carbocyclic sugar key intermediates. The modified base may provide conformational advantage to achieve better nucleoside mimetics and may also help in increasing the drug-like properties. In this manuscript, we report the use of acetamidine hydrochloride to synthesize 6-methyl-4-amino-pyrazolo[3,4-d]pyrimidine base and regioselective synthesis of six new carbocyclic nucleosides (6a-f) for antiviral evaluation. Theoretical investigations were carried out on the basis of thermodynamic and kinetic stability using MM based energy optimizations and QM based transition state search for the significant regioselectivity, which was further experimentally analyzed by NOE and UV spectroscopy.

This review is an attempt to compile the literature of various synthetic procedures of pyrimidine analogs. Pyrimidine and its fused pyrimidine derivatives are a class of heterocyclic scaffolds that demonstrates a broad range of biological and pharmacological activities such as anticancer, anxiolytic, antioxidant, antiviral, antifungal, anticonvulsant, antidepressant, and antibacterial activities. According to World Health Organization reports, cancer remains a major cause of death in worldwide and there is a need to develop an effective drug against cancer. The literature indicated that pyrimidine motifs acts as anticancer agents, which motivates the researchers to design a series of pyrimidine heterocycles.

A convenient route towards heteroacenes, interesting for use in organic electronic applications, is presented.

A series of novel 1-arylpyrazolo[3,4-d]pyrimidine derivatives, containing an amide moiety, was synthesised by condensation of different acids with 1-(2,4-dichlorophenyl)-1H-pyrazolo[3,4-d]pyrimidin-4-amine. This intermediate was prepared from 5-amino-1-(2,4-dichlorophenyl)-1H-pyrazole-4-carbonitrile by condensation with triethyl orthoformate and then cyclisation with ammonium hydroxide solution in tetrahydrofuran at room temperature. In addition, the molecular structure of a 1-arylpyrazolo[3,4-d]pyrimidine containing an amide moiety was determined by single crystal X-ray diffraction.

A one pot two step methodology for the synthesis of ten derivatives of 5-arylpyrrolo[2,3-d]pyrimidine has been reported. The methodology exploits the strong reducing nature of alkaline Na2S2O4 solution coupled with favorability of Michael type addition reaction in alkaline medium. The methodology demands attraction as it is non-catalytic, quite general for wide range of nitrostyrenes and possesses comprehensive advantages over most of the earlier methods in terms of reaction time as well as yield. The methodology enjoys additional advantage of utilizing cheaper and easily available chemicals as reagent for the purpose. Some of the synthesized compounds are found to possess remarkable activity against some of the tested bacterial strains.

A facile and straightforward approach for the synthesis of polysubstituted pyrimidine derivatives via metal-free direct amination of cinnamaldehyde derivatives with amidines is developed using molecular oxygen as green oxidant.

This one-pot, two-step protocol proceeds via Pd-catalyzed direct CH-arylation followed by a saponification—decarboxylation reaction.

A facile method has been developed for the preparation of densely functionalized tricyclic fused pyrimidine derivatives by three-component [3+2+1] cyclization. Fairly good yields of the products (up to 88%), the ready availability of the low-cost starting materials, the catalyst-free and mild conditions are the main advantages of this method.

The analogous imino-variant of the Nazarov reaction suffers from unfavorable energetics associated with the ring closure process, thereby limiting the utility of this class of reactions. In this report, the realization of the first intermolecular interrupted imino-Nazarov reaction utilizing silylated pyrimidine derivatives as nucleophilic trapping partners culminated in an expedient synthetic route to carbocyclic nucleoside analogues. The potential application of silylated nucleobases to intercept the oxyallyl cation in other variants of the Nazarov reaction provides vast opportunities to develop new strategies for the formation of carbocyclic nucleoside analogues.

The Cu-catalyzed Diels—Alder reaction of 1,3-dienes with nitroso compounds bearing a pyrimidine or pyrazine substituent is achieved with high enantioselectivities using DTBM-Segphos as ligand.

The motivation behind the present work is to synthesize some nonionic surfactants containing heterocyclic nucleus with intermediate fatty compounds for improving their surfactants properties. 2-Cyano-N-octadecylacetamide was utilized as key intermediate for the synthesis of some new thiazole, pyrazole, oxazole, pyrimidine, 1,3-dithiolane, thiophene, coumarin, oxazine and pyridazine derivatives. The newly synthesized compounds undergo propoxylation using propylene oxide to afford nonionic surface active agents. The antimicrobial and surface activities were evaluated and characterized through investigations of their spreading behavior in monolayer on water.

A very simple and facile one-pot method for the synthesis of pyrimidine derivatives is presented. In this method, 2-aryl-pyrimidine derivatives were prepared by the reaction of ketene N,S-acetal 1 with commercially available aryl aldehydes by heating under solvent and catalyst-free conditions. The synthesized pyrimidine derivatives showed blue-green fluorescence in solid state.

The synthesis of novel tricyclic fused pyrano[2,3-d]pyrido[1,2-a]pyrimidines containing both biologically active pyridopyrimidine and pyranopyrimidine scaffolds, via the reaction of 2H-pyrido[1,2-a]pyrimidine-2,4(3H)-dione, isocyanides, and dialkylacetylenedicarboxylates are reported. The products were obtained in good to excellent yields over short reaction times and with a simple work-up procedure.